Swiss Chard, Raisin, and Pine Nut Tart

Bring raisins and water to a boil in a 1-quart heavy saucepan, then remove from heat and let stand, covered, 1 hour. Drain in a colander, then pat dry with paper towels. Put oven rack in middle position and preheat oven to 400°F.
Blanch chard in a large pot of boiling salted water, uncovered, stirring occasionally, until tender but still bright green, about 5 minutes. Transfer chard with a slotted spoon to a large bowl of ice and cold water to stop cooking. Drain chard in a colander, then squeeze out excess water by handfuls. Coarsely chop chard.
Whisk together egg, cream, granulated sugar, zest, and a pinch of salt in a large bowl. Stir in pine nuts, raisins, and chard until combined.
Roll out larger piece of dough on a lightly floured surface with a lightly floured rolling pin into a 15- by 11-inch rectangle and fit into tart pan (do not trim edges). Chill shell while rolling out top.
Roll out smaller piece of dough on a lightly floured surface with lightly floured rolling pin into a 12- by 9-inch rectangle. Spread chard filling evenly into shell, then top with second rectangle of dough. Using a rolling pin, roll over edges of pan to seal tart and trim edges, discarding scraps. Cut 3 steam vents in top crust with a paring knife, then put tart in pan on a baking sheet. Bake until top is golden, about 1 hour. Transfer to a rack and cool 10 minutes, then remove side of pan. Cool to room temperature, about 1 hour. Dust with confectioners sugar.